230SL Fuel Injection Pump Cold Start Solenoid Adjustment

[wwheeler]

OK thanks. I just wired a momentary switch from a power source and directly to the CSV solenoid along with the factory wire from the relay. See any problem with that as far as feedback through the circuit? Seems to work ok but I do not want to burn up the TTS.

I am still trying to determine the correct length of time to activate before starting. I had been doing only a second or two but that is with the Starting solenoid engaged. Doesn't fire right up yet and requires a 3-4 second crank. Is your 4-5 second CSV activation with or w/o the start solenoid?

Thanks.

[rgafitanu@gmail.com]

I wired the momentary switch directly to the relay contacts and not to another source in order to avoid any unintentional shorts or other + feedback. It is possible that you may energize something else. To make sure you will have to analyze your schematic to see where else the positive that you wired will go.
I may not have been too accurate with my description of "firing immediately", let me explain.
Before this wiring modification, I would turn the ignition on for 3 sec., watch the fuel pressure gauge get up, activate the starter and it would crank 4-5 seconds before any of the cylinders to actually fire (the time needed for the CSV spray to reach the cylinders). I would still keep the starter on for another 1-2 sec to get more cylinders firing before a throttle push would make the engine run on its own.
After the wiring mod, I push the "spritz" switch for 4-5 sec. with the ignition on and then engage the starter. The cylinders start firing immediately and I can push the throttle right then to get the engine running.
The IP start solenoid is still operational, I have not started testing disconnecting it yet.

[Shvegel]

Another mod that I did on my car before it came apart for restoration was to install a fuel pressure regulator/acumulator from an 80's saab 900 in the return line of the pump that not only regulated the fuel pressure at 2.5 bar(37) psi but also hand a small accumulator built into it which allowed some leakage at the injectors and since it's opening point was above the vapor pressure of the "Gasoline" didn't allow any leakage at the delivery valves of the pump. This is essentially how Bosch solved vapor lock one and for all with the later CIS cars.  The drawback is the original pump is not high pressure enough to make this work so you have to use a later CIS pump as well.

[wwheeler]

To give some feedback on the cabin push button for the CSV vs. using the starting solenoid. While I do still have a cabin switch for the starting solenoid where I can manually control it, I now never use it. What I done instead is to lengthen the time I press the CSV button just before cranking and just do not use the start solenoid.  If it hasn’t been started in a few days, I hold the button down for 3 secs or so and give a half pedal on the accelator. Starts magically and stays runnning!

If the engine has been off for a few hours, I usually just give it a blast for a second or two with the half pedal. Again works very well. I believe the half pedal is better because it allows more turbulence in the intake to mix the air and fuel for a better start.   

For hot starts, I do not use an extra CSV blast or the start solenoid as it has always started very well under those conditions. In the past, using the start solenoid during a hot start resulted in an overly rich condition.